LED device and manufacturing method thereof

ABSTRACT

In an LED device, an opening portion of a package in which a plurality of five light-emitting elements are mounted is filled with a transparent epoxy resin and sealed with the resin. The transparent epoxy resin is shrunk when cured. Hence, the surface of the transparent epoxy resin is dented in the center portion so that the outer edge portion becomes higher than the center portion. The light-emitting elements located at opposite ends are the highest in element height among the five light-emitting elements. Hence, when the light-emitting elements are mounted at opposite ends of a single row, distances from light-emitting surfaces of the five light-emitting elements to the surface of the transparent epoxy resin are made uniform and luminous intensity distribution characteristics thereof are made uniform. Tips of leads are further bent up along side surfaces of the package. Hence, when the LED device is soldered onto a mount board, solder is deposited even on the up-bent tips of the leads, so that surface tension of solder is balanced on the front and rear of the package. As a result, the LED device can be mounted in a predetermined position while prevented from sliding. In an LED lead frame, hanger leads are provided so as to be extended in three directions of a package. Hence, the electrically conductive leads can be bent stably and accurately without tottering of the package in the process of bending the electrically conductive leads.

[0001] The present application is based on Japanese Patent ApplicationsNo. 2001-265422, 2001-265423 and 2001-265424, which are incorporatedherein by reference.

BACKGROUND OF THE INVENTION

[0002]1. Field of the Invention

[0003] The present invention relates to a light-emitting diode lamp(hereinafter referred to as “LED lamp”) in which a single light-emittingelement or a plurality of light-emitting elements, and leads and wireselectrically connected to the single or plurality of light-emittingelement(s) are packed in a package such as a synthetic resin package andsealed with a light-transmissive material such as a transparent epoxyresin. Incidentally, in this specification, an LED chip itself is called“light-emitting element” whereas a light-emitting device having aplurality of LED chips mounted therein is collectively called“light-emitting diode lamp” or “LED lamp”, further, more comprehensivelycalled “LED device”. A lead frame as a raw material thereof is called“LED lead frame”.

[0004] 2. Description of the Related Art

[0005] A surface mounting chip LED (SMD) type LED lamp has beenheretofore used in a light source for a backlight unit, or the like. Inthe SMD type LED lamp, a plurality of metal leads disposed in aninjection-molded synthetic resin package, and a plurality of lightemitting elements mounted on one of the leads and electrically connectedto the other leads by wire-bonding are entirely sealed with atransparent epoxy resin or the like.

[0006] In the LED lamp having such a plurality of light-emittingelements, however, luminous intensity distribution characteristic variesin accordance with the respective light-emitting elements. Moreover,heat-radiating characteristic is worsened compared with that of apackage of a single light-emitting element. Hence, the respectivelight-emitting elements become uneven both in heat-radiatingcharacteristic and in light-emitting efficiency. In addition, therearises a problem that color-mixing characteristic is worsened when aplurality of light-emitting elements different in wavelength are mountedin the LED lamp.

[0007] Further, in this LED lamp, however, lead portions (LED loads) bywhich the lamp is bonded on the mount board via solder is made flat. Theviscosity of solder is reduced instantaneously when the LED lamp is madeto pass through a reflow furnace at a high temperature in order tosolder the LED lamp onto the mount board. For this reason, surfacetension of solder is applied on the lead portions but the LED lamp ishardly positioned because the lead portions are so flat that the LEDlamp slides. For this reason, in the LED lamp having such leads bentonce, there is a problem that accurate mounting can be hardly made.

[0008] Still further, an example of a related-art LED lead frame for theLED lamp will be described with reference to FIG. 7. FIG. 7 is a planview showing the configuration of the related art LED lead frame.

[0009] As shown in FIG. 7, in the LED lead frame 21, four electricallyconductive leads 25 a, 25 b, 25 c and 25 d are protruded inward from anouter frame 23 so that an injection-molded synthetic resin package 22 isfixed to tips of the leads. A plurality of light-emitting elements aremounted in the package 22, electrically connected to the LED lead frame21 by wire-bonding and then sealed with a scaling resin. Thus, a bodyportion of an LED lamp is produced. Then, the electrically conductiveleads 25 a, 25 b, 25 c and 25 d are cut into a predetermined length andthen bent along the outer circumference of the package 22. Thus, asurface-mountable LED lamp is obtained.

[0010] In the LED lead frame 21, however, nothing supports the package22 after the electrically conductive leads 25 a, . . . , and 25 d arecut. Therefore, the package 22 must be fixed by a jig or something whenthe electrically conductive leads 25 a, . . . , and 25 d are to be bentback or forth along the outer circumference of the package 22. For thisreason, there is fear that the package 22 may be broken. Moreover, theelectrically conductive leads 25 a, . . . , and 25 d cannot be bentaccurately because the package 22 cannot be fixed firmly. Hence, thereis a problem that, inconsistency in positioning accuracy with respect toa partner member may occur in a post-process.

SUMMARY OF THE INVENTION

[0011] Therefore, an object of the present invention is to provide anSMD type LED device in which uniformity of luminous intensitydistribution characteristic in respective light-emitting elements andimprovement both in heat radiating characteristic and in color-mixingcharacteristic can be achieved.

[0012] Another object of the present invention is to provide an LEDdevice which can be positioned stably without sliding of the LED devicewhen soldered onto a mount board and which can be mounted on the mountboard accurately.

[0013] Still another object of the present invention is to provide amethod for manufacturing an LED device lead frame in which electricallyconductive leads can be bent with stable accuracy while a package isfixed firmly without being damaged in a process of bending theelectrically conductive leads, and an LED device lead frame used formanufacturing the LED device.

[0014] (1) According to the invention, there is provided an LED devicehaving: a plurality of light-emitting elements sealed with alight-transmissive material in a package, wherein: the plurality oflight-emitting elements are arranged in a single row in the inside of anopening portion of the package and in order of element height so that alight-emitting element higher in element height is disposed on a outerside of the single row; and the inside of the opening portion of thepackage is sealed with the light-transmissive material.

[0015] The light-transmissive material for sealing the inside of theopening portion of the package is shrunk when cured from a liquid state.For this reason, the surface of the light-transmissive material in thecenter portion of the package is dented so that the outer side of thepackage becomes higher than the center portion. Accordingly, when theplurality of light-emitting elements are arranged in such order ofelement height that a light-emitting element higher in element height isdisposed on an outer side of the single row, distances from lightemitting surfaces of the respective light-emitting elements to thesurface of the light-transmissive material are made uniform, so thatluminous intensity distribution characteristic is made uniform.

[0016] In this manner, in the LED device having a plurality oflight-emitting elements sealed with a light-transmissive material in apackage, luminous intensity distribution characteristic can be improved.

[0017] (2) According to the invention, in the LED device having theconfiguration defined in (1), one shoot of electrically conductive leadfor mounting the plurality of light-emitting elements protrudes out ofthe package to thereby form a protrusion provided in a center portion ofthe package.

[0018] With such a configuration, distances from the respectivelight-emitting elements to a heat-radiating portion are made uniform, sothat heat radiation is made uniform. Accordingly, light-emittingefficiency is made uniform, so that the LED device can be provided as anexcellent LED device.

[0019] (3) According to the invention, in the LED device having theconfiguration defined in (1) or (2), the opening portion has itsperiphery constituted by slopes provided in a lengthwise direction ofthe package and slopes provided in a widthwise direction of the package,and the slopes provided in the lengthwise direction are different ininclination from the slopes provided in the widthwise direction so thatthe inclination of the slopes provided in the widthwise direction isgentler.

[0020] With such a configuration, the opening portion is formed so thatlight is not diffused in the lengthwise direction but light is diffusedin the widthwise direction. Hence, it is easy to guide light into a thinlight guide plate. This contributes to increase in luminance of abacklight unit. In addition, when a plurality of such LED devices areused, color mixing characteristic of adjacent LED devices is improved.

[0021] (4) According to the invention, in the LED device having theconfiguration defined in any one of (1) through (3), the plurality oflight-emitting elements are different in wavelength of emitted light andare arranged in a single row at intervals of a narrow pitch.

[0022] With such a configuration, color-mixing characteristic of thelight-emitting elements is improved in all wavelengths of emitted light,so that good color-mixing characteristic is obtained when light in fullcolor is emitted from the LED device.

[0023] (5) According to the invention, in the LED device having theconfiguration defined in any one of (1) through (4), the plurality oflight-emitting elements include at least one red light emitting element,at least one green light-emitting element, and at least one bluelight-emitting element.

[0024] In this manner, when the LED device is constituted by three colortypes of light emitting elements for emitting light in red, green andblue which are light's three primary colors, the LED device can be usedas a light source for a backlight unit because white light is emittedfrom the LED device. In addition, because the opening portion is formedso that light is diffused in the widthwise direction, it its easy toguide light into a thin light guide plate. Hence, the LED devicecontributes to increase in luminance of a backlight unit.

[0025] (6) According to the invention, in the LED device having theconfiguration defined in any one of (1) through (5), the plurality orlight-emitting elements include two red light-emitting elements disposedon outer sides respectively, two blue light-emitting elements disposedon inner sides of the two red light-emitting elements respectively, andone green light-emitting element disposed in a center of the single row.

[0026] Each of a red light-emitting element and a blue light-emittingelement is lower in luminance than a green light-emitting element.Hence, when two red light-emitting elements and two blue-light-emittingelements are used, the three colors are balanced to obtain white lightemission in a state of uniform heat load balance. Moreover, because ablue light-emitting element is superior in light-emitting efficiency toa green light-emitting element, the LED device is suitable for thepurpose of requiring bluish white light or for the purpose of requiringelectric power saving. In addition, a red light-emitting element ishigher in element height than each of a green light-emitting element anda blue-light-emitting element. Hence, when the red light-emittingelements are disposed on outermost sides respectively, distances fromlight-emitting surfaces of the respective light-emitting elements to thesurface of the sealing material dented in the center portion are madeuniform, and luminous intensity distribution characteristic is improved.

[0027] (7) According to the invention, there is provided an LED devicehaving: a package; a plurality of leads; a plurality of light-emittingelements electrically connected to the plurality of leads; and alight-transmissive material with which the plurality of leads and theplurality of light-emitting elements are sealed in the package; wherein:protrusions of the plurality of leads pulled down out of the package arebent back and forth and/or left and right along a lower surface of thepackage; and tips of the plurality of bent leads are further bent upalong side surfacer of the package.

[0028] Hence, when the LED device is soldered onto a mount board, solderis deposited even on the tips of the leads bent up along the sidesurfaces of the package. Surface tension of solder is balanced on thefront and rear or left and right of the package while the skirts ofsolder are widened. Hence, the LED device can be mounted in apredetermined position while prevented from sliding.

[0029] In this manner, because the leads are bent up, that is, benttwice, surface tension of solder is balanced on the front and rear orleft and right of the package while the skirts of solder are widened.Hence, the positioning accuracy of the LED device is improved, so thatthe LED device can be mounted accurately.

[0030] (8) According to the invention, in the LED device having theconfiguration defined in (7), protrusions of the plurality of leads arebent back and forth along a lower surface of the package, and tips ofthe plurality of bent leads are further bent up along side surfaces ofthe package.

[0031] In this manner, because the direction of bending of the leads islimited to a back-and forth direction, solder can be deposited on thepackage along the lengthwise direction of the package when the LEDdevice is mounted. Hence, the length on which surface tension of thesolder is applied is elongated so that more strongly balanced force isapplied on the LED device. As a result, the LED device can be positionedmore accurately when mounted.

[0032] (9) According to the invention, there is provided an LED leadframe for producing an LED device having a single light-emitting elementor a plurality of light-emitting elements sealed with alight-transmissive material in a package, having: a plurality ofelectrically conductive leads for mounting the single light-emittingelement or the plurality of light-emitting elements packed in thepackage, the plurality of electrically conductive leads being protrudedout from one side of the package and connected to an outer frame of theLED lead frame; and a plurality of hanger leads protruded out from threesides of the package other than the one side of the package andconnected to the outer frame.

[0033] In the LED load frame configured as described above, even afterthe electrically conductive leads are cut into a predetermined length,the package is fixed to the outer frame by the hanger leads extended inother three directions. Accordingly, also in a process of banding backor forth the electrically conductive leads along the package, theelectrically conductive leads can be bent accurately without totteringbecause the package is fixed firmly. Moreover, because the package isfixed to the outer frame by the hanger leads extended in threedirections, it is unnecessary to press the package so long as the outerframe is fixed firmly. Hence, there is no fear that the package may bebroken. Incidentally, after the process of bending the electricallyconductive leads is completed, the hanger leads which have becomeunnecessary may be preferably removed.

[0034] In this manner, the LED lead frame is provided as an LED leadframe in which the electrically conductive leads can be bent with stableaccuracy while the package is fixed firmly without being damaged in theprocess of bending the electrically conductive leads.

[0035] (10) According to the invention, in the LED lead frame having theconfiguration defined in (9), ones of the plurality of hanger leads areprovided in a direction of a side which is among the three sides of thepackage and opposite to the one side of the package.

[0036] In this manner, because a plurality of hanger leads are providedin a direction of a side opposite to the one side of the package, thatis, in a direction opposite to the pulling-out direction of theelectrically conductive leads, the package can be surely prevented fromwarping when the electrically conductive leads are bent back or forthalong the package in the process of bonding the electrically conductiveleads. Hence, the electrically conductive leads can be bent more surelywith stable accuracy.

[0037] (11) According to the invention, in the LED lead frame having theconfiguration defined in (9) or (10), the ones of the plurality ofhanger leads provided in the direction of the side which is among thethree sides of the package and opposite to the one side of the packageare wide.

[0038] In this manner, because each of the hanger leads provided in adirection of a side opposite to the one side of the package, that is, ina direction opposite to the pulling-out direction of the electricallyconductive leads is made wide, stiffness becomes large. Hence, thepackage can be surely prevented from warping when the electricallyconductive leads are bent back or forth along the package in the processof bending the electrically conductive leads. Hence, the electricallyconductive leads can be bent more surely with stable accuracy.

[0039] (12) According to the invention, in the LED lead frame having theconfiguration defined in any one of (9) through (11), ones of theplurality of hanger leads provided in directions of two sides among thethree sides of the package and substantially perpendicular to theplurality of electrically conductive leads are wide.

[0040] In this manner, because each of the hanger leads provided in twodirections substantially perpendicular to the plurality of electricallyconductive leads is made wide, stiffness against warping force in thewidthwise direction becomes large. Hence, the package can be surelyprevented from warping when the electrically conductive leads are bentback or forth along the package in the process of bending theelectrically conductive leads. Hence, the electrically conductive leadscan be bent more surely with stable accuracy.

[0041] Further, using the LED lead frame according to any one of (9) to(12), an LED device described in any one of (1) to (8) or any other typeof devices may ha manufactured. The LED lead frame has at least oneelectrically conductive lead connected to one side of an outer frame ofsaid LED lead frame, and a plurality of hanger leads protruded outtoward and connected to three sides of said outer frame different fromsaid one side to which said electrically conductive lead is connected.Next, at least one light-emitting element is mounted on saidelectrically conductive lead. Further, the light-emitting element issealed with a light-transmissive material to form a package containingthe light-emitting element such that a part of said electricallyconductive lead is protruded out from said one side of said package andconnected to said outer frame. The electrically conductive lead isseparated from said outer frame. Thereafter, the electrically conductivelead is folded. In the case where a plurality of electrically conductiveleads are formed in the LED lead frame, adjacent leads are foldeddifferent in thickness direction of the LED lead frame.

[0042] Features and advantages or the invention will be evident from thefollowing detailed description of the preferred embodiments described inconjunction with the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In the accompanying drawings:

[0044]FIG. 1A is a front view showing the configuration of an LED lampaccording to an embodiment or the invention, and FIG. 1B is a sectionalview taken along the line I-I in FIG. 1A, and FIG. 1C is a sectionalview taken along the line II-II in FIG. 1A;

[0045]FIG. 2 is a circuit diagram showing the circuit configuration ofthe LED lamp according to the embodiment of the invention;

[0046]FIG. 3 is a graph showing luminous intensity distributioncharacteristic of the LED lamp according to the embodiment of theinvention;

[0047]FIG. 4 is a plan view showing the overall configuration of an LEDlead frame according to an embodiment or the invention;

[0048]FIGS. 5A, 5B, 5C and 5D are explanatory views showing a first halfof a process of bending electrically conductive leads by using the LEDlead frame according to the embodiment of the invention;

[0049]FIGS. 6A, 6B, 6C and 6D are explanatory views showing a secondhalf of the process of bending electrically conductive leads by usingthe LED lead frame according to the embodiment of the invention; and

[0050]FIG. 7 is a plan view showing the configuration of a related-artLED lead frame.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0051] An embodiment of the invention will be described below withreference to FIGS. 1A, 1B, 1C and FIGS. 2 and 3. FIG. 1A is a front viewshowing the configuration of an SMD type LED lamp according to anembodiment of the LED device of the invention. FIG. 1B is a sectionalview taken along the I-I in FIG. 1A. FIG. 1C is a sectional view takenalong the line II-II in FIG. 1A. FIG. 2 is a circuit diagram showing thecircuit configuration of the SMD type LED lamp according to theembodiment of the invention. FIG. 3 is a graph showing luminousintensity distribution characteristic of the SMD type LED lamp accordingto the embodiment of the invention.

[0052] As shown in FIG. 1A, in the SMD type LED lamp 1, one sheet ofmetal lead 3 is inserted in a synthetic resin or liquid-crystal polymerpackage 2 so that the lead 3 ranges from a left end or an openingportion 2 a of the package 2 to a right end thereof in an upper half ofthe opening 2 a. Two red light-emitting elements R1 and R2, two bluelight-emitting elements B1 and B2 and one green light-emitting elementG, i.e. five light-emitting elements in total, are mounted on the lead 3so as to be arranged at short intervals in a single horizontal row. Onthe other hand, in a lower half of the opening portion 2 a, a protrusionof the lead 3 is disposed in the nearly center portion, and five sheetsof loads 4 a, 4 b, 4 c, 4 d and 4 e are inserted in the package 2 so asto be at a distance from the lead 3. These leads 3, 4 a, . . . , and 4 eand the package 2 are integrally formed by insert-molding the package 2in the condition that the leads 3, 4 a, . . . , and 4 e are set in aninjection-molding mold for the package 2.

[0053] The five light-emitting elements are electrically connected asfollows. Because anode-side electrodes of the red light-emittingelements R1 and R2 are on their rear surfaces respectively, the redlight-emitting elements R1 and R2 are bonded and mounted onto the lead 3by silver paste so that the anode-side electrodes are connected to thelead 3. Because cathode-side electrodes of the red light-emittingelements R1 and R2 are on their front surfaces, the cathode-sideelectrodes are bonded to the leads 4 a and 4 e by wires 5 respectively.On the other hand, because anode-side and cathode-side electrodes of theGaN type blue and groan light-emitting elements D1, D2 and G are ontheir front surfaces, all the anode-side electrodes are bonded to thedownward protrusion of the lead 3 by wires 5 respectively, and thecathode-side electrodes are bonded to the leads 4 b, 4 c and 4 d bywires 5 respectively.

[0054] Electrical connections of the five light-emitting elementsconnected as described above are shown in FIG. 2 as a circuit diagram.As shown in FIG. 2, the electric circuit of the LED lamp 1 is providedas an anode common circuit using the lead 3 as an anode-side terminal (3a). Hence, the number of terminals can be reduced, so that the size ofthe LED lamp 1 can be reduced.

[0055] As shown in FIG. 1B, the opening portion 2 a of the package 2 isfilled with a transparent epoxy resin 6 and sealed with the resin 6. Thetransparent epoxy resin 6 is shrunk when cured. Hence, as shown in FIG.1B, the surface of the transparent epoxy resin 6 is dented in the centerportion so that the outer edge portion becomes higher than the centerportion. Because the red light-emitting elements R1 and R2 are thehighest in element height among the five light-emitting elements R1, B1,G, B2 and R2, the red light-emitting elements R2 and R2 are mounted atopposite ends of the single row so that distances from thelight-emitting surfaces of the five light-emitting elements R1, B1, G,B2 and R2 to the surface of the transparent epoxy resin 6 are madesubstantially uniform or uniform. As a result, luminous intensitydistribution characteristics of the respective light-emitting elementsR1, B1, G, B2 and R2 are made uniform, so that the LED lamp 1 can beprovided as an LED lamp having excellent luminous intensity distributioncharacteristic. Moreover, color-mixing characteristic of adjacentlight-emitting elements is improved, so that the LED lamp 1 can beprovided as an LED lamp also excellent in color-mixing characteristic.

[0056] In the LED lamp 1, the lead 3 on which the light-emittingelements R1, B1, G, B2 and R2 are mounted protrudes out of the package 2to form a protrusion located in the center portion of the package 2.Hence, distances from the respective light light-emitting elements R1,B1, G, B2 and R2 to a heat-radiating portion are made uniform, so thatheat radiation is made uniform. Hence, light-emitting efficiency is madeuniform, so that the LED lamp 1 can be provided as an excellent LEDlamp.

[0057] In the LED lamp 1 according to this embodiment, the periphery ofthe opening portion 2 a of the package 2 is constituted by slopes 7 aprovided in the widthwise direction and slopes 7 b provided in thelengthwise direction. The inclination of the slopes 7 a provided in thewidthwise direction is gentle whereas the inclination of the slopes 7 bprovided in the lengthwise direction is steep. Hence, light emittedthrough the opening portion 2 a is not diffused in the lengthwisedirection but diffused in the widthwise direction. As a result, when theLED lamp 1 is used as a backlight unit, efficiency of incidence of lightonto a thin light guide plate such as a transparent acrylic plate isimproved to thereby contribute to increase in luminance of the backlightunit.

[0058] In the LED lamp 1, five light-emitting elements R1, B1, G, B2 andR2 different in wavelength of emitted light are arranged in a signalhorizontal row at intervals of a narrow pitch. Hence, color-mixingcharacteristic is improved more greatly, so that good color-mixingcharacteristic can be obtained when full-color light is emitted from theLED lamp 1.

[0059] Further, as shown in FIG. 1C, the leads 4 a, . . . , and 4 epulled down out of the package 2 are bent back or forth along a lowersurface of the package 2. Specifically, the leads 4 b and 4 d are bentforth and the leads 4 a, 4 c and 4 e are bent back. Tips of these leads4 a, . . . , and 4 c are further bent up along side surfaces of thepackage 2. That is, the leads are bent twice. When the LED lamp 1 passesthrough a reflow furnace at a high temperature in order to solder theLED lamp 1 onto a mount board 8, the viscosity of solder 9 is reducedinstantaneously. In the LED lamp 1 having such leads bent twice,however, solder 9 is deposited even on the up-bent tips of the leads 4a, . . . , and 4 e. Hence, surface tension of solder 9 is balanced onthe front and rear (left and right in FIG. 1C) of the package 2 whilethe skirts of solder 9 are widened. Hence, the LED lamp 1 can be mountedin a predetermined position while prevented from sliding.

[0060] In this manner, because the leads 4 a, . . . , and 4 e are bentup, that is, bent twice, surface tension of solder 9 is balanced on thefront and rear of the package 2 while the skirts of solder 9 arewidened. Hence, the positioning accuracy of the LED lamp 1 is improved,so that the LED lamp 1 can be mounted accurately.

[0061] In the LED lamp 1 according to this embodiment, bluish whitelight is radiated as a whole because two blue light-emitting elements B1and B2 and one green light-emitting element G are used. Moreover, theLED lamp 1 brings electric power saving because each of the bluelight-emitting elements is superior in light-emitting efficiency to thegreen light-emitting element. On the other hand, when greenish whitelight is required, two green light-emitting elements G1 and G2 and oneblue light-emitting element B may be preferably used.

[0062] Luminous intensity distribution characteristic data of the LEDlamp 1 according to this embodiment will be described below withreference to FIG. 3. FIG. 3 shows results of measurement oflengthwise-direction luminous intensity distribution characteristics ofthe light-emitting elements R1, B1, G, B2 and R2 in the LED lamp 1. Asshown in FIG. 3, the luminous intensity distribution characteristics ofthe five light-emitting elements R1, B1, G, B2 and R2 are substantiallyuniform and laterally symmetric. It is apparent that the LED lamp 1 hasexcellent luminous intensity distribution characteristic. This is basedon the fact that distances from the light-emitting surfaces of the fivelight-emitting elements R1, B1, G, B2 and R2 to the surface of thetransparent epoxy resin 6 are made uniform because the redlight-emitting elements R1 and R2 highest in element height are mountedat opposite ends of the single row as described above.

[0063] Next, a method for manufacturing the LED lamp 1 will be describedbelow with reference to FIG. 4, FIGS. 5A to 5D and FIGS. 6A to 6D. FIG.4 is a plan view showing the overall configuration of an LED lead frameused for manufacturing the LED lamp 1. In other words, this LED leadframe is an embodiment of the invention. FIGS. 5A, 5B, 5C and 5D areexplanatory views showing a first half of a process of bendingelectrically conductive leads by using the LED lead frame according tothe embodiment of the invention. FIGS. 6A, 6D, 6C and 6D are explanatoryviews showing a second half of the process of bending electricallyconductive leads by using the LED lead frame according to the embodimentof the invention.

[0064] As shown in FIG. 4, in the LED lead frame 11 according to thisembodiment, a hanger lead 13 a is extended from a left portion of anouter frame 16 and fixed to a package 2 surrounded by the outer fame 16provided in four directions, a pair of hanger leads 13 b and 13 c areextended from an upper portion of the outer frame 16 and fixed to thepackage 2, and a hanger lead 13 d is extended from a right portion ofthe outer frame 16 and fixed to the package 2. On the other hand, sixelectrically conductive leads 4 a, 4 b, 4 c, 3 a, 4 d and 4 e areextended from a lower portion of the outer frame 16 into the package 2.Tips of the electrically conductive leads are provided as leads 3 or 4 ffor mounting light-emitting elements packed in the package 2 andperforming wire-bonding.

[0065] The LED lead frame 11 configured as described above is producedas follows. After a metal plate is punched to form the hanger leads 13a, 13 b, 13 c and 13 d, the electrically conductive leads 4 a, . . . ,and 4 c and the leads 3 or 4 f as tips thereof, the package 2 isproduced in the center by injection molding a liquid crystal polymer tothereby connect the leads. Thus, the LED lead frame 11 is produced.

[0066] The process of bending the electrically conductive leads 4 a, . .. , and 4 c by using the LED lead frame 11 configured as described abovewill be described below with reference to FIGS. 5A to 5D and FIGS. 6A to6D. First, as shown in FIG. 5A, light-emitting elements are mounted inthe package 2 and wire-bonded to make electrical connections. That is,the red light-emitting element R1, the blue light-emitting element B1,the green blue light-emitting element G, the blue light-emitting elementB2 and the red light-emitting element R2 are all mounted on one sheet oflead 3 which occupies an upper half of an opening portion of the package2 and which is equivalent to a tip of one 3 a of the six electricallyconductive leads 4 a, . . . , and 4 e. Then, electrodes of thelight-emitting elements are bonded to the sheet of lead 3 and the othersheets of leads 4 f by eight wires. Thus, anode-common electricalconnection is completed. Then, the opening portion of the package 2 issealed with a transparent epoxy resin. Thus, the configuration of theLED lamp is completed.

[0067] Then, as shown in FIG. 5B, the electrically conductive leads 4 a,. . . , and 4 e are cut into a predetermined length and separated fromthe outer frame 16. In the case of a related-art LED lead frame, thepackage 2 becomes free at this stage. In the LED lead frame 11 accordingto this embodiment, the package 2 is, however, fixed firmly by thehanger leads 13 a, 13 b, 13 c and 13 d extended in three directions.Then, as shown in FIG. 5C, tips of two electrically conductive leads 4 band 4 d bent forth are bent forth substantially perpendicularly. Then,as shown in FIG. 5D, tips of the other four electrically conductiveleads 4 a, 4 c, 3 a and 4 e are bent back substantially perpendicularly.Even in the case where the electrically conductive leads 4 a, . . . ,and 4 e are bent back and forth in the this manner, the electricallyconductive leads 4 a, . . . , and 4 e can be bent accurately withouttottering because the package 2 is fixed firmly by the hanger leads 13a, 13 b, 13 c and 13 d.

[0068] Then, as shown in FIG. 6A, the electrically conductive leads 4 band 4 e are bent forth by about 45° from vicinities of their bases. Whenthe electrically conductive leads are not bent substantiallyperpendicularly at once but bent about 45° by about 45° in this manner,more accurate bending can be made. Then, as shown in FIG. 6B, the otherelectrically conductive leads 4 a, 4 c, 3 a and 4 e are bent back byabout 45°. Then, as shown in FIG. 6C, the electrically conductive leads4 b and 4 d are bent forth perfectly so as to come into contact with theouter circumference of the package 2 whereas the electrically conductiveleads 4 a, 4 c, 3 a and 4 e are bent back perfectly so as to come intocontact with the outer circumference of the package 2.

[0069] After the process of bending the electrically conductive leads 4a, . . . , and 4 e is completed as described above, the package 2 isseparated from the LED lead frame 11. First, as shown in FIG. 6D, thepair of upper hanger leads 13 b and 13 c are cut and removed. Then, thepair of residual hanger leads 13 a and 13 d are cut at points near theouter frame 6 and ends of fragments are removed from the package 2. Inthis manner, the package 2 is taken out from the LED lead frame 11.

[0070] As described above, in the LED lead frame 1 according to thisembodiment, hanger leads 13 a, 13 b, 13 c and 13 d extended in threedirections of the package 2 are provided. Hence, the electricallyconductive leads 4 a, . . . , and 4 e can be bent stably and accuratelywithout tottering of the package 2 in the process or bending theelectrically conductive leads 4 a, . . . , and 4 c. The accuracy in thebending process at this stage is very important because it has influenceon the positional accuracy with respect to a partner member in apost-process. Moreover, there is no fear that the package 2 may bebroken because it is unnecessary to press the package 2.

[0071] Further, in the LED lead frame 11 according to this embodiment,because two hanger leads are extended in a direction opposite to theelectrically conductive leads 4 a, . . . , and 4 e, the package 2 can besurely prevented from warping when the electrically conductive leads 4a, . . . , and 4 e are bent back or forth along the package 2 in theprocess of bending the electrically conductive leads 4 a, . . . , and 4e. As result, the electrically conductive leads 4 a, . . . , and 4 e canbe bent more surely with stable accuracy.

[0072] Further, in the LED lead frame 11 according to this embodiment,because each of the two hanger leads 13 a and 13 d extended indirections substantially perpendicular to the electrically conductiveleads 4 a, . . . , and 4 e is wide, stiffness becomes large. Hence, thepackage 2 can be surely prevented from warping when the electricallyconductive leads 4 a, . . . , and 4 e are bent back or forth along thepackage 2 in the process of bending the electrically conductive leads 4a, . . . , and 4 e. As result, the electrically conductive leads 4 a, .. . , and 4 e can be bent more surely with stable accuracy.

[0073] Although this embodiment has shown the case where the number ofhanger leads extended in a direction opposite to the electricallyconductive leads 4 a, . . . , and 4 e is two, the invention is notlimited thereto and the number of such hanger leads may be one or threeor more. Further, each of the hanger leads extended in a directionopposite to the electrically conductive leads 4 a, . . . , and 4 e maybe widened.

[0074] Although this embodiment has shown the case where the two hangerleads 13 a and 13 d extended in directions substantially perpendicularto the electrically conductive leads 4 a, . . . , and 4 e are widened,the two hanger leads 13 a and 13 d need not be widened.

[0075] Although this embodiment has shown the case where three colortypes of light-emitting elements for emitting light with red, green andblue which are light's three primary colors are used for forming a whiteLED device, it is a matter of course that any other color typelight-emitting element may be used, and that four or more color types oflight-emitting elements may be used, or two color types oflight-emitting elements or a plurality of one color type light-emittingelements may be used.

[0076] Although this embodiment has shown the case where aliquid-crystal polymer which is one kind of synthetic resin is used asthe material of the package, any other material such as anothersynthetic resin may be also used. The method of forming the package isnot limited to the injection molding method and any other molding methodmay be used.

[0077] Although this embodiment has shown the case where a transparentepoxy resin is used as the light-transmissive material which serves as asealing material, any other light-transmissive material such as atransparent silicone resin may be also used if the material can satisfythe conditions of fluidity and filling characteristic before curing andtransparency and strength after curing.

[0078] The configuration, shape, number, material, size, connectionrelation, etc. of other parts of the LED device or the LED lead frameare not limited to this embodiment.

[0079] (1) As described above, according to the invention, there isprovided an LED device having: a plurality of light-emitting elementssealed with a light-transmissive material in a package, wherein: theplurality of light-emitting elements are arranged in a single row in theinside of an opening portion of the package and in order of elementheight so that a light-emitting element higher in element height isdisposed on an outer side of the single row; and the inside of theopening portion of the package is sealed with the light-transmissivematerial.

[0080] The light-transmissive material for sealing the inside of theopening portion of the package is shrunk when cured from a liquid state.For this reason, the surface of the light-transmissive material in thecenter portion of the package is dented so that the outer side of thepackage becomes higher than the center portion. Accordingly, when theplurality of light-emitting elements are arranged in such order ofelement height that a light-emitting element higher in element height isdisposed on an outer side of the single row, distances fromlight-emitting surfaces of the respective light-emitting elements to thesurface of the light-transmissive material are made uniform, so thatluminous intensity distribution characteristic is made uniform.

[0081] In this manner, in the LED device having a plurality oflight-emitting elements sealed with a light-transmissive material in apackage, luminous intensity distribution characteristic can be improved.

[0082] (2) According to the invention, in the LED device having theconfiguration defined in (1), one sheet of electrically conductive leadfor mounting the plurality of light-emitting elements protrudes out ofthe package to thereby form a protrusion provided in a center portion ofthe package.

[0083] With such a configuration, in addition to the advantage describedin (1), distances from the respective light-emitting elements to aheat-radiating portion are made uniform, so that heat radiation is madeuniform. Accordingly, light-emitting efficiency is made uniform, so thatthe LED device can be provided as an excellent LED device.

[0084] (3) According to the invention, in the LED device having theconfiguration defined in (1) or (2), the opening portion has itsperiphery constituted by slopes provided in a lengthwise direction ofthe package and slopes provided in a widthwise direction of the package,and the slopes provided in the lengthwise direction are different ininclination from the slopes provided in the widthwise direction so thatthe inclination of the slopes provided in the widthwise direction isgentler.

[0085] With such a configuration, in addition to the advantage describedin (1) or (2), the opening portion is formed so that light is notdiffused in the lengthwise direction but light is diffused in thewidthwise direction. Hence, it is easy to guide light into a thin lightguide plate. This contributes to increase in luminance of a backlightunit. In addition, when a plurality of such LED devices are used,color-mixing characteristic of adjacent LED devices is improved.

[0086] (4) According to the invention, in the LED device having theconfiguration defined in any one of (1) through (3), the plurality oflight-emitting elements are different in wavelength of emitted light andare arranged in a single row at intervals at a narrow pitch.

[0087] With such a configuration, in addition to the advantage describedin any one of (1) through (3), color-mixing characteristic of thelight-emitting elements is improved in all wavelengths of emitted light,so that good color-mixing characteristic is obtained when light in fullcolor is emitted from the LED device.

[0088] (5) According to the invention, in the LED device having theconfiguration defined in any one of (1) through (4), the plurality oflight-emitting elements include at least one red light-emitting element,at least one green light-emitting element, and at least one bluelight-emitting element.

[0089] In this manner, when the LED device is constituted by three colortypes of light-emitting elements for emitting light in red, green andblue which are light's three primary colors, in addition to theadvantage described in any one of (1) through (4), the LED device can beused as a light source for a backlight unit because white light isemitted from the LED device. In addition, because the opening portion isformed so that light is diffused in the widthwise direction, it is easyto guide light into a thin light guide plate. Hence, the LED devicecontributes to increase in luminance of a backlight unit.

[0090] (6) According to the invention, in the LED device having theconfiguration defined in any one of (1) through (5), the plurality oflight-emitting elements include two red light-emitting elements disposedon outer sides respectively, two blue light-emitting elements disposedon inner sides of the two red light-emitting elements respectively, andone green light-emitting element disposed in a center of the single row.

[0091] In addition to the advantage described in any one of (1) through(5), each of a red light-emitting element and a blue light-emittingelement is lower in luminance than a green light-emitting element.Hence, when two red light-emitting elements and two blue-light-emittingelements are used, the three colors are balanced to obtain white lightemission in a state of uniform heat load balance. Moreover, because ablue light-emitting element is superior in light-emitting efficiency toa green light-emitting element, the LED device is suitable for thepurpose of requiring bluish white light or for the purpose of requiringelectric power saving. In addition, a red light-emitting element ishigher in element height than each of a green light-emitting element anda blue-light-emitting element. Hence, when the red light emittingelements are disposed on outermost sides respectively, distances fromlight-emitting surfaces of the respective light-emitting elements to thesurface of the sealing material dented in the center portion are madeuniform, and luminous intensity distribution characteristic is improved.

[0092] (7) As described above, according to the invention, there isprovided an LED device having: a package; a plurality of leads; aplurality of light-emitting elements electrically connected to theplurality of leads; and a light-transmissive material with which theplurality of leads and the plurality of light-emitting elements aresealed in the package; wherein: protrusions of the plurality of leadspulled down out of the package are bent back and forth and/or left andright along a lower surface of the package; and tips of the plurality ofbent leads are further bent up along side surfaces of the package.

[0093] Hence, when the LED device is soldered onto a mount board, solderis deposited even on the tips of the leads bent up along the sidesurfaces of the package. Surface tension of solder is balanced on thefront and rear or left and right of the package while the skirts ofsolder are widened. Hence, the LED device can be mounted in apredetermined position while prevented from sliding.

[0094] In this manner, because the leads are bent up, that is, benttwice, surface tension of solder is balanced on the front and rear orleft and right of the package while the skirts of solder are widened.Hence, the positioning accuracy of the LED device is improved, so thatthe LED device can be mounted accurately.

[0095] (8) According to the invention, in the LED device having theconfiguration defined in (7), protrusions of the plurality of leads arebent back and forth along a lower surface of the package, and tips ofthe plurality of bent leads are further bent up along side surfaces ofthe package.

[0096] In addition to the advantage described in (7), because thedirection of bending of the leads is limited to a back-and-forthdirection thus, solder can be deposited on the package along thelengthwise direction of the package when the LED device is mounted.Hence, the length on which surface tension of the solder is applied iselongated so that more strongly balanced force is applied on the LEDdevice. As a result, the LED device can be positioned more accuratelywhen mounted.

[0097] (9) As described above, according to the invention, there isprovided an LED lead frame for producing an LED device having a singlelight-emitting element or a plurality of light-emitting elements sealedwith a light-transmissive material in a package, having: a plurality ofelectrically conductive leads for mounting the single light-emittingelement or the plurality of light-emitting elements packed in thepackage, the plurality of electrically conductive leads being protrudedout from one side of the package and connected to an outer frame of theLED lead frame; and a plurality of hanger leads protruded out from threesides of the package other than the one side of the package andconnected to the outer frame.

[0098] In the LED lead frame configured as described above, even afterthe electrically conductive leads are cut into a predetermined length,the package is fixed to the outer frame by the hanger leads extended inother three directions. Accordingly, also in a process of bending backor forth the electrically conductive leads along the package, theelectrically conductive leads can be bent accurately without totteringbecause the package is fixed firmly. Moreover, because the package isfixed to the outer frame by the hanger leads extended in threedirections, it is unnecessary to press the package so long as the outerframe is fixed firmly. Hence, there is no fear that the package may bebroken. Incidentally, after the process of bending the electricallyconductive leads is completed, the hanger leads which have becomeunnecessary may be preferably removed.

[0099] In this manner, the LED lead frame is provided as an LED leadframe in which the electrically conductive leads can be bent with stableaccuracy while the package is fixed firmly without being damaged in theprocess of bending the electrically conductive leads.

[0100] (10) According to the invention, in the LED lead frame having theconfiguration defined in (9), ones of the plurality of hanger leads areprovided in a direction of a side which is among the three sides of thepackage and opposite to the one side of the package.

[0101] In this manner, because a plurality of hanger leads are providedin a direction of a side opposite to the one side of the package, thatis, in a direction opposite to the pulling-out direction of theelectrically conductive leads, in addition to the advantage described in(9), the package can be surely prevented from warping when theelectrically conductive leads are bent back or forth along the packagein the process of bending the electrically conductive leads. Hence, theelectrically conductive leads can be bent more surely with stableaccuracy.

[0102] (11) According to the invention, in the LED lead frame having theconfiguration defined in (9) or (10), the ones of the plurality ofhanger leads provided in the direction of the side which is among thethree sides of the package and opposite to the one side of the packageare wide.

[0103] In this manner, in addition to the advantage described in (9) or(10), each of the hanger leads provided in a direction of a sideopposite to the one side of the package, that is, in a directionopposite to the pulling-out direction of the electrically conductiveleads is made wide, so that stiffness becomes large. Hence, the packagecan be surely prevented from warping when the electrically conductiveleads are bent back or forth along the package in the process of bendingthe electrically conductive leads. Hence, the electrically conductiveleads can be bent more surely with stable accuracy.

[0104] (12) According to the invention, in the LED lead frame having theconfiguration defined in any one of (9) through (11), ones of theplurality of hanger leads provided in directions of two sides among thethree sides of the package and substantially perpendicular to theplurality or electrically conductive leads are wide.

[0105] In this manner, in addition to the advantage described in any oneof (9) through (11), each of the hanger leads provided in two directionssubstantially perpendicular to the plurality of electrically conductiveleads is made wide, so that stiffness against warping force in thewidthwise direction becomes large. Hence, the package can be surelyprevented from warping when the electrically conductive leads are benthark or forth along the package in the process of bending theelectrically conductive leads. Hence, the electrically conductive leadscan be bent more surely with stable accuracy.

[0106] Although the invention has been described in its preferred formwith a certain degree of particularity, it is understood that thepresent disclosure of the preferred form can be changed in the detailsof construction and in the combination and arrangement of parts withoutdeparting from the spirit and the scope or the invention as hereinafterclaimed.

1-9. (canceled)
 10. A method for manufacturing an LED device comprisingsteps of: preparing an LED lead frame having at least one electricallyconductive lead connected to one side of an outer frame of said LED leadframe, and a plurality of hanger leads protruded out toward andconnected to three sides of said outer frame different from said oneside to which said electrically conductive lead is connected; mountingat least one light-emitting element on said electrically conductivelead; sealing said light-emitting element with a light-transmissivematerial to form a package containing said light-emitting element suchthat a part of said electrically conductive lead is protruded out fromsaid one side of said package and connected to said outer frame; andseparating said electrically conductive lead from said outer frame. 11.A method for manufacturing an LED device according to claim 10, whereinones of said plurality of hanger leads are provided in a direction of aside which is among said three sides of said package and opposite tosaid one side of said package.
 12. A method for manufacturing an LEDdevice according to claim 10, wherein said ones of said plurality ofhanger leads provided in the direction of the side which is among saidthree sides of said package and opposite to said one side of saidpackage are wide.
 13. A method for manufacturing an LED device accordingto claim 10, wherein ones of said plurality of hanger leads provided indirections of two sides among said three sides of said package andsubstantially perpendicular to said plurality of electrically conductiveleads are wide.
 14. A method for manufacturing an LED device accordingto claim 10, further comprising folding said electrically conductivelead after said separating
 15. A method for manufacturing an LED deviceaccording to claim 14, wherein a plurality of electrically conductiveleads are formed in said LED lead frame, and adjacent leads are foldeddifferent in a thickness direction of the LED lead frame.